From the Guidelines
Diagnosing ALS requires a comprehensive approach, including a neurological examination, medical history review, and a series of tests to rule out other conditions with similar symptoms, with electromyography (EMG) and nerve conduction velocity being key tests in diagnosing ALS, as stated in the 2020 study by the Journal of the American College of Radiology 1. The diagnosis of ALS typically involves looking for signs of both upper and lower motor neuron damage, such as:
- Muscle weakness
- Atrophy
- Fasciculations (muscle twitching)
- Hyperreflexia
- Spasticity Diagnostic tests commonly used include:
- Electromyography (EMG) to assess electrical activity in muscles
- Nerve conduction studies to evaluate nerve function
- MRI scans to rule out other conditions like tumors or spinal cord issues
- Blood and urine tests to exclude other diseases
- Sometimes a lumbar puncture to analyze cerebrospinal fluid Genetic testing may be recommended if there's a family history of ALS, as noted in the 2020 study by the Journal of the American College of Radiology 1. The El Escorial criteria, a standardized diagnostic approach, helps classify the certainty of ALS diagnosis based on clinical findings, and MRI head without IV contrast is usually appropriate for the initial imaging of patients with suspected motor neuron disease, as recommended by the 2020 study by the Journal of the American College of Radiology 1. Since ALS symptoms can mimic other neurological disorders, diagnosis often takes time and may require multiple evaluations over several months to observe disease progression, and early diagnosis is crucial for timely intervention with medications like riluzole and edaravone, which can modestly slow disease progression, as supported by the 2020 study by the Journal of the American College of Radiology 1.
From the Research
Diagnostic Criteria for Amyotrophic Lateral Sclerosis (ALS)
The diagnostic criteria for ALS involve a combination of clinical examinations, laboratory tests, and nerve conduction/electromyography studies to exclude other conditions and confirm the diagnosis 2. The essential requirements for diagnosis are clearly defined by the El Escorial criteria, which include:
- Upper motor neuron signs, such as hyperreflexia, spasticity, and extensor plantar responses
- Lower motor neuron signs, such as muscle atrophy, fasciculations, and weakness
- Progressive spread of symptoms to other regions of the body
Clinical and Laboratory Tests
Clinical neurophysiologic tests, such as electromyography (EMG) and nerve conduction studies (NCS), are essential for diagnosing ALS 3, 4, 5. These tests can help identify:
- Axonal degeneration through nerve conduction studies
- Lower motor neuron involvement through EMG recordings with needle examination
- Upper motor neuron involvement through transcortical magnetic stimulation protocols and cortical excitability
Diagnostic Challenges
Despite the availability of diagnostic criteria and tests, ALS remains a challenging disease to diagnose, and many physicians, including neurologists, may miss the diagnosis due to lack of knowledge or diagnostic difficulty 4. A thorough understanding of the symptomatology, potential causes, progression, and treatment of ALS is essential to provide timely and high-quality patient care 3.
Exclusion of Other Conditions
The differential diagnosis must exclude non-motor neuron diseases and other adult-onset motor neuron diseases with restricted presentations, such as progressive bulbar palsy, progressive muscular atrophy, and primary lateral sclerosis 4. Laboratory tests, such as MRI and CT scans, biochemical markers, and genetic testing, can be used to exclude other diseases and confirm the diagnosis of ALS 4, 2.